Force exit workerd on exit hook

`exitHook()` must be synchronous, and we want to make sure `workerd`
is cleaned up immediately on exit

Author: mrbbot

packages/miniflare/src/index.ts

@@ -464,7 +464,9 @@ export class Miniflare {
       verbose: this.#sharedOpts.core.verbose,
     };
     this.#runtime = new Runtime(opts);
-    this.#removeRuntimeExitHook = exitHook(() => void this.#runtime?.dispose());
+    this.#removeRuntimeExitHook = exitHook(
+      () => void this.#runtime?.dispose(/* force */ true)
+    );
 
     // Update config and wait for runtime to start
     await this.#assembleAndUpdateConfig(/* initial */ true);

packages/miniflare/src/runtime/index.ts

@@ -134,14 +134,14 @@ export class Runtime {
     return this.#processExitPromise;
   }
 
-  dispose(): Awaitable<void> {
+  dispose(force = false): Awaitable<void> {
     // `kill()` uses `SIGTERM` by default. In `workerd`, this waits for HTTP
     // connections to close before exiting. Notably, Chrome sometimes keeps
     // connections open for about 10s, blocking exit. We'd like `dispose()`/
     // `setOptions()` to immediately terminate the existing process.
     // Therefore, use `SIGINT` which force closes all connections.
     // See https://github.com/cloudflare/workerd/pull/244.
-    this.#process?.kill("SIGINT");
+    this.#process?.kill(force ? "SIGKILL" : "SIGINT");
     return this.#processExitPromise;
   }
 }